Double unit spiral spring drive



June 4, 1963 H. .1. THOMSEN DOUBLE UNIT SPIRAL SPRING DRIVE Filed Aug.8, 1960 IN VEN TOR. flGWd/"J fla/fAS HTTGF/V YS nited States 57 Thisinvention relates to spring drives and particularly to a spring for adrive having two spirally wound portions adjacent to each otherinterconnected by the outer turn disposed diagonally therebetween.

Spiral springs have been constructed heretofore from flat stock woundoutwardly from a diametrically disposed securing end at the center andterminating at the outer end with an angular securing portion. The forceexerted by the spiral type spring depends upon the number of turns andthe cross sectional area of the strap material from the which the springis constructed. As the spring becomes larger in diameter with theincreasing number of turns, the power in the outer turn is reduced and amore compact and powerful spring for the diameter thereof is provided bywinding adjacent units from a single length of material in the oppositehand with the outer turns connected by a diagonal portion between theunits to produce the unit spring.

A length of material is selected to produce the proper number of turnsin each of the units with the diagonal section disposed therebetween.The ends of the strip are placed adjacent to each other in slots in apair of rotatable shafts, one of which is driven in one direction andthe other rotated in the opposite direction at the same rate of rotationif both springs are to be of equal strength. Hold down and guidestructure is provided adjacent to the rotatable arbors so as to forcethe strap material to be bent around the arbors as they are rotated towind the ends of the material in the opposite direction thereon with astraight securing end at the center of each spring unit. After the unitsare wound as tight as possible with the diagonal portion of the strapvmaterial therebetween, the arbors are moved outwardly of each other tohave the ends released from the central holding portion at the center ofthe units so that the spring may drop from the winding machine.

Since each of the units are wound in a direction opposite to the other,the winding of one unit from the center will carry the winding actionacross the outer diagonal turn to the second unit which is wound fromthe outside inwardly to provide an increased rotatable =force on a shafthaving a slot in the end which receives the central diametrical securingend at the center of the units. The spring produces a compact unit forconnecting aligned shafts to apply a force from one shaft through thespring unit to the other shaft to produce a drive thereto through thespring. This is a new concept in providing a drive through a spring fromone shaft to a second shaft which is disposed in aligned relation to thefirst shaft.

Accordingly, the main objects of the invention are: to form a drivebetween two aligned shafts through a spring having two spiral unitswound in opposite directions to each other and interconnected by aportion of the outer turn of the strap from which the units are wound;to form a spring from a pair of spirally wound units constructed from ahairpin shaped length of stock by winding the ends thereof on alignedarbors in opposite directions at the same speed of rotation to have thesame number of turns in each unit which are interconnected by thediagonally disposed outer portion of the stock; to provide a pair ofspiral wound spring units interconnected by an outer turn for joining apair of aligned shafts in a manner to have the rotation of one shaftapply a force in rotation to the other shaft in the same direction and,in general, to provide a spiral spring having two adjacent atent iceunits which are wound' simultaneously in the opposite direction andwhich is simple in construction, positive in operation, and economicalto manufacture.

Other objects and features of novelty of the invention will bespecifically pointed out or will become apparent when referring, for abetter understanding of the invention, to the following descriptiontaken in conjunction with the accompanying drawing, wherein:

:FIGURE 1 is a view in elevation of a spring of a-double spiral unit'type embodying features of the present invention;

FIG. 2 is a side view of the spring illustrated in FIG. '1;

FIG. 3 is a sectional view of the structure illustrated in FIG. 2, withthe ends of the spring disposed on the ends of adjacent shafts, and

FIG. 4 is a view of a machine for winding the spring illustrated inFIGS. 1 to 3.

The spring of the present invention consists of two spirally wound unitshaving aligned centers and an outer turn which is continuous anddiagonally disposed from one unit to the other. The ends of the springsare located on the center line of each spiral unit and the units arewound in the opposite direction so that when one unit is wound, thewinding will carry over to the other unit which is also wound.

As illustrated in FIG. 4, a pair of axially movable rotatable arbors 9and 10 have slots 11 in their adjacent end for receiving the ends 12 ofa hairpin shaped length of spring strip stock 13. The ends 12 aredisposed between hold down elements 14 which maintain the strip in ahorizontal plane as the arbors 9 and 10 are rotated in oppositedirections. Arbor 9 is driven by a gear .15 from a gear 16 secured to adriven shaft -17 driven by a belt and pulley drive '18. The shaft alsodrives a gear 19 through an idler or reversing gear .21 to drive a gear22 connected to the arbor 10 for driving it in the opposite direction tothe gear 15 and arbor 9. When driven from the shaft '17, the arbors 9and .10 operate at the same speed and in opposite directions to wind theends 12 thereon until the outer turn 23 is disposed on a diagonalbetween the wound units 24 and 25. The piston rod of rams 26 is thenwithdrawn within the cylinders and the arbors 9 and :10 are moved apartto permit the spring unit 27, as illustrated in FIGS. 1 to 3 inclusive,to drop from the arbors. The arbors are then moved to adjacent positionsand a new hairpin shaped length of stock 13 has its ends 12 disposedbeneath the hold down element .14 and inserted in the slots -11 in theend of the arbors '9 and 10 which are rotated in opposite directions towind another spring composed of two spiral units having its endsterminating on a common center.

The spring unit 27 thus constructed has the unit 24 connected to a driveshaft 28 by having the central diametrically extending end 29' disposedwithin a slot 31 in the end thereof. The unit 25 has its diametricallyextending end portion 32 disposed in a slot 33 in a driven shaft 34. Therotation of the shaft 28 in a clockwise direction will wind up the turnsof the spring uni-t 24 and apply a force to the diagonal outer turn 23to wind up the spring unit 25 inwardly from the outer turn to therebybuild up a substantial force through both spring units for rotating theshaft 34. Similarly, when the shaft 34 is rotated in a counterclockwisedirection, the spring unit 25 is wound to produce a pulling force on thediagonal outer turn portion 23 to wind up the spring unit 24 to apply acounterclockwise rotational force to the shaft 28 when it is to bedriven by the spring.

Thus a very compact type of spring is produced through the provision oftwo units wound in opposite directions with the terminal ends of thespring disposed on the diameter of the inner turns of the units. Thissubstantially decreases the diameter of the spring and pro- PatentedJune 4, 1963 vides a saving in the length of stock due to the smallerdiameter of the turns of each unit.

What is claimed is:

1. A spring drive including a spring interconnecting a pair ofsubstantially aligned shafts, said spring comprising a pair of adjacentspirally wound units containing a plurality of turns joined by an outerturn diagonally disposed thereacross, the ends of the spring beingdisposed at the center of the units, said pair of substantially alignedshafts having adjacent ends secured to the ends of said units.

2. A spring drive including a spring interconnecting a pair ofsubstantially aligned shafts, said spring comprising a pair of adjacentspirally wound units containing a plurality of turns joined by an outerturn diagonally disposed thereacross, diametrically extending ends oneach unit at the center thereof, said pair of substantially alignedshafts having adjacent ends connected to the ends of the units.

3.A spring drive including a spring interconnecting the ends of a pairof substantially aligned shaits, said spring comprising a pair ofadjacent spirally Wound units containing a plurality of turns joined byan outer t-unu diagonally disposed thereacross, one unit being wound inone direction, the other unit being wound in the opposite direction, anddiametrically extending ends at the center of the units, said pair ofsubstantially aligned shafts having slotted ends engaged by the ends ofthe units.

References Cited in the file of this patent UNITED STATES PATENTS1,804,705 Paulus et a1 May 12, 1931 1,897,412 Adams Feb. 14, 19331,917,486 'Beck July 1, 1933 2,754,580 Schlaich July 17, 1956 2,821,379Donkin et al Ian. 28, 1958 FOREIGN PATENTS 570,987 France Jan. 24, 1924126,429 Sweden Aug. 18, 1949 90,435 Sweden Oct. 5, 1957

1. A SPRING DRIVE INCLUDING A SPRING INTERCONNECTING A PAIR OFSUBSTANTIALLY ALIGNED SHAFTS, SAID SPRING COMPRISING A PAIR OF ADJACENTSPIRALLY WOUND UNITS CONTAINING A PLURALITY OF TURNS JOINED BY AN OUTERTURN DIAGONALLY DISPOSED THEREACROSS, THE ENDS OF THE SPRING BEINGDISPOSED AT THE CENTER OF THE UNITS, SAID PAIR OF SUBSTANTIALLY ALIGNEDSHAFTS HAVING ADJACENT ENDS SECURED TO THE ENDS OF SAID UNITS.